Users Guide

dcb stack-unit all pfc-buffering pfc-ports 64 pfc-queues 2

NOTE: To save the pfc buering conguration changes, save the conguration and reboot the system.

NOTE: Dell Networking OS Behavior: DCB is not supported if you enable link-level ow control on one or more interfaces.

For more information, refer to Flow Control Using Ethernet Pause Frames.

Conguring DCB Maps and its Attributes

This topic contains the following sections that describe how to congure a DCB map, apply the congured DCB map to a port,

congure PFC without a DCB map, and congure lossless queues.

DCB Map: Conguration Procedure

A DCB map consists of PFC and ETS parameters. By default, PFC is not enabled on any 802.1p priority and ETS allocates equal

bandwidth to each priority. To congure user-dened PFC and ETS settings, you must create a DCB map.

1. Enter global conguration mode to create a DCB map or edit PFC and ETS settings.

CONFIGURATION mode

dcb-map name

2. Congure the PFC setting (on or o) and the ETS bandwidth percentage allocated to trac in each priority group, or whether

the priority group trac should be handled with strict priority scheduling. You can enable PFC on a maximum of two priority

queues on an interface. Enabling PFC for dot1p priorities makes the corresponding port queue lossless. The sum of all allocated

bandwidth percentages in all groups in the DCB map must be 100%. Strict-priority trac is serviced rst. Afterwards,

bandwidth allocated to other priority groups is made available and allocated according to the specied percentages. If a priority

group does not use its allocated bandwidth, the unused bandwidth is made available to other priority groups.

DCB MAP mode

priority-group group_num {bandwidth percentage | strict-priority} pfc {on | o}

Example: priority-group 0 bandwidth 60 pfc o priority-group 1 bandwidth 20 pfc on priority-group 2 bandwidth 20 pfc on

priority-group 4 strict-priority pfc o

Repeat this step to congure PFC and ETS trac handling for each priority group.

3. Specify the dot1p priority-to-priority group mapping for each priority. Priority-group range: 0 to 7. All priorities that map to the

same queue must be in the same priority group.

DCB MAP mode

priority-pgid dot1p0_group_num dot1p1_group_num dot1p2_group_num dot1p3_group_num

dot1p4_group_num dot1p5_group_num dot1p6_group_num dot1p7_group_num

Leave a space between each priority group number. For example: priority-pgid 0 0 0 1 2 4 4 4 in which priority group 0 maps

to dot1p priorities 0, 1, and 2; priority group 1 maps to dot1p priority 3; priority group 2 maps to dot1p priority 4; priority group 4

maps to dot1p priorities 5, 6, and 7.

Important Points to Remember

• If you remove a dot1p priority-to-priority group mapping from a DCB map (no priority pgid command), the PFC and ETS

parameters revert to their default values on the interfaces on which the DCB map is applied. By default, PFC is not applied on

specic 802.1p priorities; ETS assigns equal bandwidth to each 802.1p priority.

As a result, PFC and lossless port queues are disabled on 802.1p priorities, and all priorities are mapped to the same priority queue

and equally share the port bandwidth.

Data Center Bridging (DCB)